Method for making circuit board

ABSTRACT

A method for making the same is disclosed. First, a first substrate and a second substrate are provided. The first substrate includes a release film attached to a carrier. The second substrate includes a copper film covered with a solder mask. Second, the solder masked is patterned. Next, the release film and the patterned solder mask are pressed together so that the first substrate is attached to the second substrate. Then, the copper film is patterned to form a first pattern and a second pattern. The first pattern is in direct contact with the release film and the second pattern is in direct contact with the patterned solder mask. Later, a passivation is formed to cover the first pattern and the second pattern to form a circuit board structure. Afterwards, a package is formed on the carrier to form a packaging structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims the benefitof U.S. patent application Ser. No. 12/835,746, filed Jul. 14, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method for making a circuitboard structure, the circuit board structure and a package structureobtained therefrom. In particular, the present invention is directed toa method for making a circuit board structure and a package structure bymeans of a carrier with an attached release film to support a copperfilm covered with a solder mask to the circuit board structure and thepackage structure.

2. Description of the Prior Art

A circuit board is an essential component of an electronic device. Withthe trend of always scaling down the size of the electronic devices,various carrier structures are therefore proposed to support the die.Some pins extend outwards to connect other circuits surrounding thecircuit board to form proper electrical connections.

As far as the current technology is concerned, a circuit structurecalled “lead frame” is conventionally known. FIGS. 1-4 illustrate amethod for making a traditional lead frame. Please refer to FIG. 1,first a metal substrate 101 is provided. Second, please refer to FIG. 2,the metal substrate 101 is patterned to form a circuit pattern 110 and adie pad 111 which correspond to a die (not shown). Later, via holes 122are formed, pins 120 are connected to the metal substrate 101 as well aspins 120 and the die pad 111 are plated with silver 121. Next, pleaserefer to FIG. 3, the die 130 is attached to the die pad 111 thenfollowed by a wire bonding step and a tin plating step. Afterwards,please refer to FIG. 4, the pins are shaped to obtained a packagestructure 102. The data in the die is connected with the outer circuitsby the pins 120.

However, as the data processed by the die increases and the speed forprocessing needs to be higher, the lead frame as illustrated cannotprovide more pins 120 to meet the demands because the space around thedie is so limited. In such a way, the application of the traditionallead frame 102 as a result is restricted.

FIG. 5 illustrates another carrier structure 201 for supporting dies. Inthe carrier structure 201, the circuit patterns 220 are respectivelydisposed on both opposite sides of the substrate 210. In addition, thesolder mask layer 230 is selectively disposed on both opposite sides ofthe substrate 210 to properly protect the circuit pattern 220. Apartfrom this, some of the circuit pattern 220 is exposed. In the carrierstructure 201, independent solder mask layers 231/232 need to be formedon both opposite sides of the substrate 210. The patterns of the soldermask layers 231/232 are usually distinctively different so that they cancope with different demands, such as location, of die pads (not shown)and different solder balls (not shown).

After the carrier structure 201 for supporting dies as illustrated inFIG. 5 undergoes suitable packaging steps, the package structure 202 asillustrated in FIG. 6 is obtained. In addition to the substrate 210, thecircuit pattern 220, the solder mask layer 230, and the solder masklayers 231/232 as illustrated in FIG. 5, there are an extra die pad 221,die 240, bonding wire 250, sealant material 200 and solder balls 270 inthe package structure 202 as illustrated in FIG. 6 due to the subsequentpackaging steps.

The die 240 is disposed on the die pad 221 within the circuit pattern220 and surrounded by the solder mask layer 231 at the same time as wellas electrically connected to other parts of the circuit pattern 220 bymeans of the bonding wires 250. The sealant material 200 completelycovers the die pad 221, the die 240, the bonding wire 250 and partiallycovers the substrate 210 and the solder mask layer 230. The solder balls270 are surrounded by the solder mask layer 232. In both the carrierstructure 201 for supporting dies as illustrated in FIG. 5 and thepackage structure 202 as illustrated in FIG. 6, the solder mask layers231/232 are independently disposed on two opposite sides of thesubstrate 210 and extend to the margins of the substrate 210.

In the light of the above-mentioned carrier structures, the packagestructures and the conventional methods for making lead frames are notyet perfect, thus other novel carrier structures, package structures andthe fabrication methods are still needed to provide a much simplerstructure and to be free from conventional pin count restrictions.

SUMMARY OF THE INVENTION

The present invention hence proposes a novel circuit board structure, anovel package structure and the novel fabrication methods thereof. Thecircuit board structure and the package structure of the presentinvention employ a one-side-patterned solder mask so the total structureand the fabrication methods are much simplified. Besides, the circuitboard structure and the package structure of the present invention canbreak the restriction of insufficient pins encountered in the prior artin order to keep pace with the demands for more pins when the dataprocessed by the die increases and the speed for processing needs to behigher.

The present invention in a first aspect proposes a method for making acircuit board structure. First, a first substrate and a second substrateare provided. The first substrate includes a release film attached to acarrier. The second substrate includes a copper film covered with afirst solder mask. Second, the first solder mask is patterned on oneside only. Next, the release film and the patterned first solder maskare pressed together so that the first substrate is attached to thesecond substrate. Then, the copper film is patterned to form a firstpattern and a second pattern. The first pattern is in direct contactwith the release film and the second pattern is in direct contact withthe patterned first solder mask. Later, a first protective layer isformed to cover the first pattern and the second pattern to form acircuit board structure.

In one embodiment of the present invention, the first pattern is a diepad and the second pattern is a circuit pattern which is protected bythe patterned solder mask. In another embodiment of the presentinvention, a second solder mask may be formed to selectively cover thesecond pattern. In still another embodiment of the present invention, apackaging structure may be formed to be disposed on the carrier. In afurther embodiment of the present invention, the release film and thecarrier may be optionally removed to expose the first pattern and thepatterned solder mask to obtain another packaging structure.

The present invention in a second aspect proposes a circuit boardstructure. The circuit board structure of the present invention includesa carrier, a release film, a patterned solder mask, a first conductivepattern, a second conductive pattern and a protective layer. The releasefilm is attached to the carrier. The single-side-patterned solder maskis disposed on the release film and in direct contact with the releasefilm. The first conductive pattern is disposed on the release film andin direct contact with the release film. The second conductive patternis disposed on the release film, adjacent to the first conductivepattern and in direct contact with the patterned solder mask. Theprotective layer covers the first conductive pattern and the secondconductive pattern.

The present invention in a third aspect proposes a circuit boardstructure. The circuit board structure of the present invention includesa carrier, a release film, a patterned solder mask, a first conductivepattern, a second conductive pattern, a covering solder mask and aprotective layer. The release film is attached to the carrier. Thesingle-side-patterned solder mask is disposed on the release film and indirect contact with the release film. The first conductive pattern isdisposed on the release film and in direct contact with the releasefilm. The second conductive pattern is disposed on the release film,adjacent to the first conductive pattern and in direct contact with thepatterned solder mask. The covering solder mask selectively covers thesecond conductive pattern. The protective layer covers the firstconductive pattern and the second conductive pattern.

The present invention in a fourth aspect proposes a package structure.The package structure of the present invention includes a sealantmaterial, a single-side-patterned solder mask, a first conductivepattern, a second conductive pattern, a first protective layer, a secondprotective layer, a die and a bonding wire. The patterned solder mask isdisposed on a surface of the sealant material. The first conductivepattern is disposed on the same surface as the sealant material. Thesecond conductive pattern is disposed in the sealant material, adjacentto the first conductive pattern and in direct contact with the patternedsolder mask. The first protective layer is completely disposed in thesealant material and covers the first conductive pattern and the secondconductive pattern. The second protective layer completely covers thefirst conductive pattern. The die is completely disposed in the sealantmaterial and on the first pattern. The bonding wire is also completelydisposed in the sealant material and selectively electrically connectsthe die and the first conductive pattern.

The present invention in a fifth aspect proposes another packagestructure. The package structure of the present invention includes asealant material, a single-side-patterned solder mask, a firstconductive pattern, a second conductive pattern, a covering solder mask,a first protective layer, a second protective layer, a die and a bondingwire. The patterned solder mask is disposed on a surface of the sealantmaterial. The first conductive pattern is disposed on the same surfaceas the sealant material. The second conductive pattern is disposed inthe sealant material, adjacent to the first conductive pattern and indirect contact with the patterned solder mask. The covering solder maskcompletely covers the second conductive pattern. The first protectivelayer is completely disposed in the sealant material and covers thefirst conductive pattern. The second protective layer is disposedcompletely outside the sealant material, covers the first conductivepattern. The die is completely disposed in the sealant material and onthe first pattern. The bonding wire is also completely disposed in thesealant material and selectively electrically connects the die and thefirst conductive pattern.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 illustrate a method for making a traditional lead frame.

FIG. 5 illustrates another traditional carrier structure for supportingdies.

FIG. 6 illustrates a traditional package structure.

FIGS. 7-11 illustrate the method for making a circuit board structure ofthe present invention.

FIG. 12 illustrates a first embodiment of an extension method for makingthe pre-package structure of the present invention.

FIG. 12A illustrates another embodiment of an extension method formaking the pre-package structure of the present invention with anadditional covering solder mask of the circuit board structure.

FIG. 13 illustrates a first embodiment of an extension method for makingthe pre-package structure of the present invention.

FIG. 13A illustrates a second embodiment of an extension method formaking the pre-package structure of the present invention with anadditional covering solder mask of the circuit board structure.

FIG. 14 illustrates an extension method for making the package structureof the present invention.

FIG. 14A illustrates a second embodiment of the package structure of thepresent invention with an additional covering solder mask of the circuitboard structure.

DETAILED DESCRIPTION

The present invention in a first aspect provides a first embodiment ofthe method for making a circuit board structure. FIGS. 7-11 illustratethe method for making the circuit board structure of the presentinvention. Please refer to FIG. 7, initially a first substrate 310 and asecond substrate 320 are provided. The first substrate 310 and thesecond substrate 320 may be prepared separately. They can be laminatedtogether to form a single substrate (not shown) when needed. The firstsubstrate 310 includes a carrier 311, and a release film 312 which isattached to one side of the carrier 311. The second substrate 320includes a copper film 321 with a thickness of about 10 μm-70 μm,preferably 10 μm-35 μm. Only one side of the copper film 321 is coveredwith a solder mask 322.

The carrier 311 may be any suitable material, such as polyethyleneterephthalate (PET), polycarbonate (PC), polymethylmethacrylate (PMMA)or a copperless substrate. The release film 312 may be a plastic andsticky material and has better adhesion to the carrier 311. The releasefilm 312 accordingly adheres to one side of the carrier 311 by means ofsuch adhesion. For a trial production, on one hand the release film 312may be applied to the carrier 311 by means of screen printing. On theother hand, for a mass production, the release film 312 may be appliedto the carrier 311 by means of rollers.

Second, please refer to FIG. 8. Before the first substrate 310 and thesecond substrate 320 are pressed together, the solder mask 322 ispatterned in advance. The solder mask 322 may be patterned by means ofconventional lithography or laser opening . . . etc. The pattern on thesolder mask 322 may be previously designed to go with the demands of thelater steps. For example, the patterning procedure is only carried outon one side of the solder mask 322 to obtain a single-side-patternedsolder mask 322.

Then, please refer to FIG. 9, the release film 312 and the patternedsolder mask 322 may be pressed together so that the first substrate 310is attached to the second substrate 320. Because the release film 312may be a plastic and sticky material, in one embodiment of the presentinvention, the patterned solder mask 322 is embedded into the releasefilm 312 when the first substrate 310 is attached to the secondsubstrate 320. Accordingly, the copper film 321 is in direct contactwith the release film 312. In addition, because the release film 312 hasa stronger adhesion to the carrier 311, there is a weaker adhesionbetween the release film 312 and the patterned solder mask 322. At themoment, one side of the copper film 321 is exposed.

Next, please refer to FIG. 10. In a first embodiment, because one sideof the copper film 321 is still exposed, the copper film 321 will have apattern such as a first pattern 325, a die pad 328 and a second pattern326 once the copper film 321 is suitably patterned. The copper film 321may be patterned by a wet film method or by a dry film method. The firstpattern 325 and the second pattern 326 each may have differentfunctions. In one embodiment of the present invention the first pattern325 may be a connecting pad and the second pattern 326 may be a circuitpattern 326 which is protected by the patterned solder mask 322. Inother words, the second pattern 326 corresponds to the patterned soldermask 322. As a result, shown in FIG. 10, the first pattern 325 is indirect contact with the release film 312 but the second pattern 326 isin direct contact with the patterned solder mask 322.

In a second embodiment of the present invention for making a circuitboard structure as shown in FIG. 10A, a covering solder mask 327 may beoptionally formed to completely cover the first pattern 325, the die pad328 and the second pattern 326. The covering solder mask 327 may serveas a protection layer of the second pattern 326 to be followed with,please refer to FIG. 10B, the covering solder mask 327 is patterned toexpose the needed element (s). For example, the covering solder mask 327is patterned to expose the first pattern 325, the die pad 328 and tocover the second pattern 326 so the covering solder mask 327 may serveas the protection layer of the second pattern 326.

Afterwards, as shown in FIG. 11 a first protective layer 323 should beformed on the surface of the copper film 321 in order to protect thefragile copper film 321. Because there are the first pattern 325 and thesecond pattern 326 of different functions on the patterned copper film321, the first protective layer 323 covers the first pattern 325 and thesecond pattern 326, too. A method such as an electroplating step may beused to form the first protective layer 323 on the surface of the copperfilm 321. The first protective layer 323 may be a composite materiallayer. For instance, the first protective layer 323 may include at leastone of Ni, Ag and Au, to form a Ni/Au protective layer.

Or alternatively, as shown in FIG. 11A, in order to protect the fragilecopper film 321 a first protective layer 323 should be formed on thesurface of the copper film 321 so the first protective layer 323 coversthe first pattern 325 and the die pad 328. A method such as anelectroplating step may be used to form the first protective layer 323on the surface of the copper film 321. The first protective layer 323may be a composite material layer. For instance, the first protectivelayer 323 may include at least one of Ni, Ag and Au, to form a Ni/Auprotective layer.

After the aforesaid steps, the laminated first substrate 310 and secondsubstrate 320 together form a novel circuit board structure 301. Pleaserefer to FIG. 11, illustrating a first embodiment of the circuit boardstructure 301 proposed by the present invention and FIG. 11A illustratesa second embodiment of the circuit board structure 301 of the presentinvention. The circuit board structure 301 of the present inventionincludes the carrier 311, the release film 312, a patterned solder mask322, a first conductive pattern 325, a second conductive pattern 326 anda first protective layer 323. Providing the circuit board structure 301further includes a covering solder mask 327, it is illustrated in FIG.11A, which is a second embodiment of the circuit board structure 301provided by the present invention.

As described earlier, the release film 312 is attached to the carrier311 with a stronger adhesion therebetween. The patterned solder mask 322is disposed on the release film 312 and in direct contact with therelease film 312. In one embodiment of the present invention, when thepatterned solder mask 322 of the second substrate 320 is attached to therelease film 312 of the first substrate 310, preferably the patternedsolder mask 322 is embedded in the release film 312. The firstconductive pattern 325 and the second conductive pattern 326 arerespectively disposed on the release film 312. On one hand, the firstconductive pattern 325 is in direct contact with the release film 312.On the other hand, the second conductive pattern 326 is in directcontact with the patterned solder mask 322. In other words, the secondconductive pattern 326 corresponds to the patterned solder mask 322.Further, the first conductive pattern 325 and the second conductivepattern 326 are often adjacent to each other or arranged in an alternateorder. The first protective layer 323 covers the first conductivepattern 325 and the second conductive pattern 326. The first protectivelayer 323 may include at least one of Ni, Ag and Au, to form a compositeNi/Au protective layer.

In another embodiment of the present invention, the circuit boardstructure 301 as illustrated in FIG. 11 may further become a pre-packagestructure 303 after a pre-package step. FIG. 12 illustrates a firstembodiment of an extension method for making the pre-package structureof the present invention; FIG. 12A illustrates another embodiment of anextension method for making the pre-package structure of the presentinvention with an additional covering solder mask 327 of the circuitboard structure 301. Please refer to FIGS. 12 and 12A, a package 330 maybe further formed on the carrier 311 of the circuit board structure 301as illustrated in FIGS. 11 and 11A. For example, the die 331 is firstadhered to a first pattern 325, that is, the die pad 328. For example, asilver paste or a thermal-dissipating material (not shown) is used toattach the die 331 onto the first pattern 325. Then, bonding wires 332,such as copper wires, silver wires, gold wires or gold-plated copperwires, are used to optionally connect the die 331 to part of the firstpattern 325 electrically. After the electrical connection is completed,a sealant material 333, such as an epoxy resin, may be employed tohermetically seal the die 331 and the bonding wires 332 to keep the die331 and the bonding wires 332 from the atmosphere, such as humidity.

As shown in FIG. 12, the sealant material 333 not only hermeticallyseals the die 331 and the bonding wires 332, the sealant material 333but also in direct contact with the release film 312 and the patternedsolder mask 322. As shown in FIG. 12A, the sealant material 333hermetically seals the covering solder mask 327. The circuit boardstructure 301 as illustrated in FIG. 11 may further become a pre-packagestructure 303 as shown in FIG. 12 after a package 330 is further formedon the carrier 311.

In still another embodiment of the present invention, the pre-packagestructure 303 as illustrated in FIG. 12 may further become a pre-packagestructure 305 after another pre-package step. FIG. 13 illustrates anfirst embodiment of an extension method for making the pre-packagestructure of the present invention; FIG. 13A illustrates a secondembodiment of an extension method for making the pre-package structureof the present invention with an additional covering solder mask 327 ofthe circuit board structure 301. Please refer to FIGS. 13 and 13A. Thecarrier 311 and the release film 312 may be respectively removed fromthe pre-package structure 303 as illustrated in FIGS. 12 and 12A toobtain the pre-package structure 305.

Please note that the carrier 311 and the release film 312 can be easilyremoved form the pre-package structure 303 without jeopardizing otherparts of the pre-package structure 303 because the release film 312 hasa stronger adhesion to the carrier 311 and a relatively weaker adhesionto the patterned solder mask 322. At this moment, the patterned soldermask 322 is selectively disposed between the first pattern 325. Afterthe carrier 311 and the release film 312 is removed from the pre-packagestructure 303, the patterned solder mask 322 and the first pattern 325in the pre-package structure 305 are exposed.

In order to protect the fragile copper film of the first pattern 325, instill another embodiment of the present invention, the pre-packagestructure 305 shown in FIG. 13 may further become a package structure307 after a packaging step. FIG. 14 illustrates an extension method formaking the package structure of the present invention. Please refer toFIG. 14, a second protection layer 324 may be further formed on thefirst pattern 325 in the pre-package structure 305 shown in FIG. 13 tocompletely cover the first pattern 325. The second protection layer 324may include at least one of Ni, Ag and Au, or an OSP (OrganicSolderability Preservative) to form a Ni/Au protective layer.

After the aforesaid steps, a novel package structure 307 is obtained.Please refer to FIG. 14, illustrating a first embodiment of the packagestructure 307 of the present invention; FIG. 14A illustrates a secondembodiment of the package structure 307 of the present invention with anadditional covering solder mask 327 of the circuit board structure 301.In the package structure 307 of the present invention, there are apatterned solder mask 322, a first conductive pattern 325, a secondconductive material 326, a first protective layer 323, a secondprotective layer 324, a die 331, a bonding wire 332 and a sealantmaterial 333.

In the package structure 307 of the present invention as shown in FIG.14, it is observed that the patterned solder mask 322 is disposed on onesurface of the sealant material 333. The patterned solder mask 322 ispartially in contact with the sealant material 333 and partiallyexposed. The sealant material 333 is usually a hermetical material, suchas an epoxy resin. The first conductive pattern 325 is disposed on thesame surface as the patterned solder mask 322 is on the sealant material333. The first conductive pattern 325 usually serves to define the diepad for the die 331. The second conductive material 326 is also disposedin the sealant material 333 and defines a circuit pattern. Further, thesecond conductive material 326 is also indirect contact with thepatterned solder mask 322 and protected by the patterned solder mask322. In other words, the second conductive material 326 corresponds tothe patterned solder mask 322. In addition, the second conductivematerial 326 is adjacent to the first conductive pattern 325 and indirect contact with the patterned solder mask 322. In FIG. 14A, thecovering solder mask 327 directly covers the second conductive material326.

In one aspect, the first protection layer 323 is completely disposed inthe sealant material 333 and covers the first conductive pattern 325 andthe second conductive material 326. In another aspect, the secondprotection layer 324 is completely disposed outside the sealant material333 and completely covers the first conductive pattern 325. The firstprotection layer 323 and the second protection layer 324 mayindependently include at least one of Ni, Ag and Au, or an OSP (OrganicSolderability Preservative). The die 331 is disposed on the firstconductive pattern 325 and optionally electrically connected to thefirst conductive pattern 325 by the bonding wire 332. The die 331 andthe bonding wire 332 are simultaneously disposed in the sealant material333 to form a package. Other features of the package structure 307 ofthe present invention, such as the package, may refer to the abovedescriptions and will not be repeated here.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A method for making a circuit board, comprising:providing a first substrate and a second substrate, wherein said firstsubstrate comprises a release film which is attached to a carrier, andsaid second substrate comprises a copper film which is covered with asolder mask; patterning said solder mask; pressing said release film andsaid patterned solder mask together so that said first substrate isattached to said second substrate; patterning and removing said copperfilm to simultaneously form a first pattern, a die pad and a secondpattern, wherein said first pattern is in direct contact with saidrelease film and said second pattern is in direct contact with saidpatterned solder mask, wherein said solder mask only covers a bottomsurface of said second pattern and a bottom surface of said die pad; andforming a protective layer to cover said first pattern and said secondpattern to form a circuit board structure.
 2. The method for making acircuit board of claim 1, wherein said second pattern is a circuitpattern which is protected by said patterned solder mask.
 3. The methodfor making a circuit board of claim 2, further comprising: forming asecond solder mask which selectively covers said second pattern.
 4. Themethod for making a circuit board of claim 1, wherein said secondpattern corresponds to said patterned solder mask.
 5. The method formaking a circuit board of claim 1, further comprising: forming apackaging structure disposed on said carrier.
 6. The method for making acircuit board of claim 5, wherein said packaging structure comprises: adie disposed on said die pad; a bonding wire selectively andelectrically connecting said die and said first pattern; and a sealantmaterial hermetically sealing said die and said bonding wire and indirect contact with said patterned solder mask and said release film. 7.The method for making a circuit board of claim 5, further comprising:removing said release film and said carrier at the same time to exposesaid first pattern and said patterned solder mask.